Utilization of artificial neural networks and autoregressive modeling in diagnosing mitral valve stenosis.

This research is concentrated on the diagnosis of mitral heart valve stenosis through the analysis of Doppler Signals' AR power spectral density graphic with the help of ANN. Multilayer feedforward ANN trained with a Levenberg Marquart backpropagation algorithm was implemented in the MATLAB environment. Correct classification of 94% was achieved, whereas 4 false classifications have been observed for the test group of 68 subjects in total. The designed classification structure has about 97.3% sensitivity, 90.3% specifity and positive prediction is calculated to be 92.3%. The stated results show that the proposed method can make an effective interpretation.

Imaging system for visualization and numerical analysis of cancer at stomach and skin tissues.

Digital imaging of cancerous cells is instrumental not only in determining the characteristic of the cancer but also monitoring the progress of the disease in the follow up of the patient and adapting the treatment, accordingly. Therefore, we have developed an imaging system to display and layout the characteristics of normal and cancerous cells in an automated way. Image processing techniques are performed on the digitized images of stomach and skin tissues, in order to derive the number of cells, area of an individual cell, and average area of the cells in a certain size of an image window.

Comparison of the autoregressive modeling and fast Fourier transformation in demonstrating Doppler spectral waveform changes in the early phase of atherosclerosis.

In this study, we have performed fast Fourier transformation (FFT) and autoregressive (AR) signal processing of the Doppler signals at a nonstenotic arterial site in patients with atherosclerosis and healthy volunteers. We have not only utilized Doppler sonograms, but also facilitated the power spectral density distribution graphs using AR modeling and FFT. Our preliminary analysis show that AR modeling has a higher efficacy in demonstrating Doppler spectral waveform changes in the preclinic or silent phase of atherosclerosis. AR has especially revealed an outstanding difference in the calculation for frequency level of maximum power spectral density.

Investigation of a new heart contractility power parameter.

First derivative of arterial blood pressure, dp/dt is known to reflect the contractility power of the heart. We hypothesize that the calculated area under each cardiac cycle of the blood pressure curve is also another practical tool in revealing the heart contractility power. Of the 84 subjects, 61 patients were found to have adequate contractility power (high dp/dt) and their mean area calculation resulted in 64.2 mmHg s with a standard deviation of 2.9 mmHg s. The remaining 23 patients have indicated poor heart contractility power (low dp/dt) and stayed in serious condition for long time. This group had mean area of 41.4 +/- 3.1 mmHg s. Patients with poor contractility power had areas below 45 mmHg s, while all area calculations for patients with high contractility power stayed over 60 mmHg s. Therefore, small area of the arterial blood pressure curves seems to be a good indicator of a poor heart contractility power and the area calculation may be an adjunct parameter to the dp/dt that has been employed for the assessment of heart contractility.

Sphincter muscle stimulator to be used before treating anal atresia.

Closed rectum is a very frequently encountered anomaly of the newborns in our university hospital. Before making a rectal opening, the anorectal sphincter muscle needs to be stimulated to prevent any damage to the muscle itself In this study, we have designed a stimulator that provides reasonably constant output current depending on the physiological impedance of the rectal area. The current amplitude can be set between 20 and 250 mA. Stimulation pulses are adjusted for duration of 230 micros and can be obtained at a repetition period between 1.75 and 20 ms. Fifteen patients in the Pediatric Surgery Department of Erciyes University Hospital were subjected to our stimulation tests. On average, about 140 mA was enough to stimulate the muscle when probes were applied over the skin. On the other hand, with the placement of probes beneath the skin, stimulation was obtained for pulse amplitude of 40 mA.

Low-cost instrumentation for the diagnosis of Hirschsprung's disease.

In Hirschsprung's disease, the internal anorectal sphincter fails to relax in response to rectal distension, which strongly indicates the absence of rectoanal inhibitory reflex (RAIR). Hirschsprung's disease is a very common case particularly encountered in the newborns in our region. Development of a manometric system targeted specifically for the diagnosis of this disease at a reasonable cost is an urgent need identified by our regional colorectal surgeons. These surgeons indicated that commercially available anorectal manometers are too expensive to acquire. Therefore, in our research we tried to develop a low-cost single balloon-transducer system, which only provides information about RAIR, and hence diagnoses the Hirschsprung's disease. The hardware part of our instrumentation is made of a latex balloon, pressure transducer, amplifier, and A/D converter circuits, which all collects the pressure readings and sends the data to the computer. The manometer system software, programmed based on Delphi, displays these readings and patient information on a computer screen. This designed system was successful enough to perform manometric recording of RAIR in the anorectal ampulla of rabbits and rats.